The present invention relates to a combustion apparatus for gas turbines and, more particularly, to a combustion apparatus having excellent durability.
In a gas turbine apparatus for use in electric power plants, there has been a demand to cope reduce pollution by reducing, harmful components contained in exhaust gas. It has been proposed to inject water or steam into the combustion chamber to reduce nitrogen oxides NOx.
In the combustion apparatus where water or steam is injected for the purpose of reducing NOx, various problems are raised in comparison with the case where the water injection is not utilized.
A water injection nozzle is generally combined with a burner for normally feeding fuel. One problem relating to water injection occurs at a liner cap member connecting the burner and a combustion apparatus liner body. Since a part of the water spray is introduced into the combustion gas but a portion of the water spray also enters into the through a spacing and holes formed in the liner cap member for cooling air. The introduction of water through the air cooling holes adversely affects the liner cap member, thereby reducing the service life of the liner cap member. More particularly, when water droplets from the water injection adheres to the metal members which are subjected to direct radiated heat of the combustion flame, the metal members are locally subjected to very large thermal stress, causing a cracking therein.